<?php
// +----------------------------------------------------------------------
// | ThinkPHP [ WE CAN DO IT JUST THINK ]
// +----------------------------------------------------------------------
// | Copyright (c) 2006-2012 http://thinkphp.cn All rights reserved.
// +----------------------------------------------------------------------
// | Licensed ( http://www.apache.org/licenses/LICENSE-2.0 )
// +----------------------------------------------------------------------
// | Author: liu21st <liu21st@gmail.com>
// +----------------------------------------------------------------------

defined('THINK_PATH') or exit();
/**
 * Sqlite缓存驱动
 * @category   Extend
 * @package  Extend
 * @subpackage  Driver.Cache
 * @author    liu21st <liu21st@gmail.com>
 */
class CacheSqlite extends Cache {

	/**
	 * 架构函数
	 * @param array $options 缓存参数
	 * @access public
	 */
	public function __construct($options=array()) {
		if ( !extension_loaded('sqlite') ) {
			throw_exception(L('_NOT_SUPPERT_').':sqlite');
		}
		if(empty($options)) {
			$options = array (
                'db'        =>  ':memory:',
                'table'     =>  'sharedmemory',
			);
		}
		$this->options  =   $options;
		$this->options['prefix']    =   isset($options['prefix'])?  $options['prefix']  :   C('DATA_CACHE_PREFIX');
		$this->options['length']    =   isset($options['length'])?  $options['length']  :   0;
		$this->options['expire']    =   isset($options['expire'])?  $options['expire']  :   C('DATA_CACHE_TIME');

		$func = $this->options['persistent'] ? 'sqlite_popen' : 'sqlite_open';
		$this->handler      = $func($this->options['db']);
	}

	/**
	 * 读取缓存
	 * @access public
	 * @param string $name 缓存变量名
	 * @return mixed
	 */
	public function get($name) {
		N('cache_read',1);
		$name   = $this->options['prefix'].sqlite_escape_string($name);
		$sql    = 'SELECT value FROM '.$this->options['table'].' WHERE var=\''.$name.'\' AND (expire=0 OR expire >'.time().') LIMIT 1';
		$result = sqlite_query($this->handler, $sql);
		if (sqlite_num_rows($result)) {
			$content   =  sqlite_fetch_single($result);
			if(C('DATA_CACHE_COMPRESS') && function_exists('gzcompress')) {
				//启用数据压缩
				$content   =   gzuncompress($content);
			}
			return unserialize($content);
		}
		return false;
	}

	/**
	 * 写入缓存
	 * @access public
	 * @param string $name 缓存变量名
	 * @param mixed $value  存储数据
	 * @param integer $expire  有效时间（秒）
	 * @return boolen
	 */
	public function set($name, $value,$expire=null) {
		N('cache_write',1);
		$expire =  !empty($expireTime)? $expireTime : C('DATA_CACHE_TIME');
		$name  = $this->options['prefix'].sqlite_escape_string($name);
		$value = sqlite_escape_string(serialize($value));
		if(is_null($expire)) {
			$expire  =  $this->options['expire'];
		}
		$expire	=	($expire==0)?0: (time()+$expire) ;//缓存有效期为0表示永久缓存
		if( C('DATA_CACHE_COMPRESS') && function_exists('gzcompress')) {
			//数据压缩
			$value   =   gzcompress($value,3);
		}
		$sql  = 'REPLACE INTO '.$this->options['table'].' (var, value,expire) VALUES (\''.$name.'\', \''.$value.'\', \''.$expire.'\')';
		if(sqlite_query($this->handler, $sql)){
			if($this->options['length']>0) {
				// 记录缓存队列
				$this->queue($name);
			}
			return true;
		}
		return false;
	}

	/**
	 * 删除缓存
	 * @access public
	 * @param string $name 缓存变量名
	 * @return boolen
	 */
	public function rm($name) {
		$name  = $this->options['prefix'].sqlite_escape_string($name);
		$sql  = 'DELETE FROM '.$this->options['table'].' WHERE var=\''.$name.'\'';
		sqlite_query($this->handler, $sql);
		return true;
	}

	/**
	 * 清除缓存
	 * @access public
	 * @return boolen
	 */
	public function clear() {
		$sql  = 'DELETE FROM '.$this->options['table'];
		sqlite_query($this->handler, $sql);
		return ;
	}
}